Low cost high bit rate transceiving technique for optical networks

Abstract

Technique for low cost delivery of a high bit rate electric signal via an optical network, by using a group of optical channels in the network for respectively delivering there-through a number of component electric signals of the high bit rate signal, The optical channels are respectively associated with different wavelengths, and each of the optical channels comprises optical elements suitable for conducting an optical signal having bandwidth significantly narrower than bandwidth of any of the component signals. The high bit rate electric signal is then successively restored from the optical signals delivered via the optical channels.

1 . A method for delivery of a high bit rate electric signal via an optical network, by using a group of optical channels in said network for respectively delivering there-through a number of component electric signals of the high bit rate signal, wherein the optical channels being respectively associated with different wavelengths, each of the optical channels comprising optical elements suitable for conducting an optical signal having bandwidth significantly narrower than bandwidth of any of said component signals, the method further comprises restoring the high bit rate electric signal from said optical signals delivered via said optical channels. 
     
     
         2 . The method according to  claim 1 , for transmitting the high bit rate electric signal from a transmitting site to a receiving site, the method comprising
 dividing the high bit rate electric signal into the number of said component electric, intermediate bit rate signals,   converting said electric component intermediate bit rate signals into respective said optical signals, each of the optical signals having substantially narrowed bandwidth in comparison with that of a corresponding component electric signal ;   carrying said optical signals over respective said optical channels to the receiving site, and   restoring a corresponding received component signal from each said optical signal upon receiving thereof at the receiving site, for further obtaining a restored high bit rate signal from respective received component signals, wherein the restored high bit rate signals is substantially identical to the transmitted high bit rate signal.   
     
     
         3 . The method according to  claim 2 , comprising providing each of said optical channels, at the transmitting site, with bandwidth (BW) narrowing means comprising an electric to optic (E/O) modulator having a linear characteristics between its input power and its output power and at the receiving site, with restoration means for restoring said received component signal from said received optical signal, the restoration means comprising an optic to electric (O/E) photodiode and an amplifier, each of the latter having a linear characteristics between its input power and its output power, the restoration means also comprising an analog to digital (A/D) converter and a digital signal processing (DSP) block. 
     
     
         4 . The method according to  claim 1 , wherein the bandwidth of said optical signal is narrower than the bandwidth required for adequate transmission of the corresponding component electric signal. 
     
     
         5 . The method according to  claim 1 , wherein a bandwidth compression coefficient is approximately between 2.5 and 4. 
     
     
         6 . A unit for transmitting and receiving high bit rate signals carrying data via an optical network, the unit comprising one or both of the following:
 a transmitter side, for providing a first group of component electric signals of a transmitted high bit rate signal, for transmitting said first group of component electric signals in the form of a respective first grip of optical signals via a first group of optical channels;   per each of the optical channels, the transmitter side comprising electric to optic (E/O) optical elements suitable for converting a specific component electric signal into an optical signal carrying data of said specific component electric signal but having bandwidth essentially narrower than bandwidth of said specific component signal,   a receiver side, for receiving a second group of optical signals carrying data over a respective second group of optical channels, the receiver side, per each optical channel of the second group, comprising optic to electric (O/E) optical elements for converting a particular optical signal of the second group into a corresponding component electric signal of a second group, and elements for digitizing said component electric signal and restoring data carried by said particular optical signal,   wherein bandwidth of any optical signal of the second group is significantly narrower than bandwidth of any component electric signal of the second group.   
     
     
         7 . The unit according to  claim 6 , further comprising
 means for dividing said transmitted high bit rate electric signal into said first group of component, intermediate bit rate, electrical signals,   means for assembling a received high bit rate electric signal from the component electric signals of the second group, having intermediate bit rates.   
     
     
         8 . The unit according to  claim 6 , wherein
 the transmitter side comprises said E/O optical elements forming E/O converters, for narrowing bandwidth of said component electric signals of the first group;   the receiver side comprises said O/E optical elements forming O/E converters, and also comprises amplifiers, analog to digital (A/D) converters and digital signal processing (DSP) blocks for compensating inter-symbol interference (ISI) of data carried by the received optical signals of the second group.   
     
     
         9 . The unit according to  claim 6 , wherein at least said E/O optical elements and said O/E optical elements have linear conversion characteristics between input and output power, with linearity of said characteristics being not lower than 2 5  levels of conversion per bit. 
     
     
         10 . The unit according to  claim 6 , designed for transmitting the high bit rate electric signal of about 100-112 Gbps coded using OOK coding, said component intermediate bit rate signals of first and/or second groups are four signals of about 25-28 Gbps, and each of the optical signals has bandwidth of about 10 GHz. 
     
     
         11 . The transceiver according to  claim 8 , wherein the transmitted high bit rate signal is a 100 Gbps OOK coded signal, and wherein at least one of the E/O converters of the transmitter side comprises a continuous wavelength (CW) laser, and a 10 GH modulator comprising an electro absorption modulator(EAM) or Mach-Zehnder interferometer (MZI);
 the receiver side, for at least one optical channel, comprises the O/E converter including an avalanche photo diode APD or a PIN diode,   the amplifier being a trans-impedance amplifier TIA,   the A/D converter and the digital signal processing DSP block utilizing Maximum Likelihood Sequence Estimation (MLSE) algorithm.